This invention relates to an applicator for granular material, and in particular to an applicator for granular agricultural chemicals such as herbicides.
The application of some agricultural chemicals, e.g. herbicides must be accurate, with a uniform distribution of the chemicals. This is particularly true of chemicals which are selective in their action. Excessive application in any given area results in the loss of expensive chemicals and may lead to crop loss. Insufficient application obviously results in the loss of treating agent, and the small quantity of chemicals applied may not effect the desired result, e.g. weed control. In many cases it is desirable to apply the treating agent to selected areas of the crop only. Moreover, the applicator must not lose chemicals while in the off condition. This problem arises most often when transporting the applicator from one location to another or when operating on rough terrain. Finally, the rate of application, i.e. output per a given unit of time of the applicator must be easily adjusted, preferably from the tractor or other applicator towing machine. Accordingly, the ideal applicator must supply a constant, uniform and readily adjustable quantity of chemicals, and be readily turned on or off.
Presently available applicators are designed primarily for the application of chemical fertilizer or crop dusts. Most such applicators perform on the basis of a reciprocating or rocking principle, which tends to result in a cyclical output of chemicals rather than a smooth continuous flow. Examples of granular material dispensers are disclosed by Canadian Pat. Nos. 511,023, issued to Sarioni Company, Inc. on Mar. 15, 1955; 569,598 issued to Allis-Chalmers Manufacturing Company on Jan. 27, 1959; 663,435, issued to Sperry Rand Corporation on May 21, 1963; 707,611, issued to D. C. Henderson on May 18, 1965; 723,490, issued to E. I. duPont de Nemours and Company on Dec. 14, 1965 and 949,391, issued to E. A. Seifert on June 18, 1974; and U.S. Pat. Nos. 2,865,536, issued to A. A. Price on Dec. 23, 1958; 3,073,607, issued to D. L. Christy on Jan. 15, 1963; 3,190,506, issued to E. M. Selzler on June 22, 1965; 3,788,529 issued to D. L. Christy on Jan. 29, 1974, and 3,858,759, issued to R. W. Lubenow on Jan. 7, 1975.
Some of the devices disclosed by the above-identified patents rely for feed control on changes in the weight or volume of the material being fed to alter motor speed. The actual feed mechanism may be an auger, apertures closed by slide valves of the type found on small commercially available lawn fertilizers, a feed roller with cavities for receiving and dispensing a quantity of granular material, or brushes extending into a hopper containing the granular material.
In some of the devices, material flows from a top hopper through holes into a smaller bottom hopper forming piles. The tops of the piles are displaced into tubes leading to spreaders by a reciprocating rod extending the length of the lower hopper and studs or washers on the rod. The result is cyclical output. Moreover, on rough terrain, the piles forming in the lower hopper tend to drop out which may cause over application or the wasting of expensive chemicals. Other applicators include trap door type devices extending the entire length of the hopper for rocking back and forth to open one side of the hopper and then the other. Such rocking action results in intermittent output which may be acceptable for chemical fertilizers, but is not acceptable for granular herbicides. Metering devices placed inside the main hopper of the applicator tend to pulverize the granular material, causing compaction within the hopper and reduced feed through the discharge orifices.
Thus, in spite of the large variety of granular feed devices presently available, as exemplified by the art discussed above, there is still a need for an uncomplicated applicator. The object of the present invention is to provide a relatively simple applicator for granular material which is easy to render operative and inoperative, and in which the rate of application can be accurately and quickly controlled.